Thermal inactivation of strawberry polyphenoloxidase and its impact on anthocyanin and color retention in strawberry (Fragaria x ananassa Duch.) purées

Strawberry (Fragaria x ananassa Duch.) cultivars were screened for their polyphenoloxidase (PPO) activities, and thermal stability of PPO was evaluated in vitro for three cultivars under different time–temperature regimes (60, 75 and 90 °C for 3 and 5 min, respectively). Heating strawberry purées should further elucidate the impact of thermal treatments on strawberry PPO in its natural matrix (‘in situ’ activity). To evaluate the consequences of PPO inactivation on anthocyanin and color stability, the purées were stored for 28 days at +20 °C monitoring the contents of monomeric, polymeric (spectrophotometrically) and individual anthocyanins (HPLC–DAD–MSⁿ) as well as color properties (CIE L*a*b*). Antioxidant activities (FRAP), total phenolic (Folin–Ciocalteu) and ascorbic acid contents of freshly prepared and stored purées, respectively, were determined spectrophotometrically. PPO activities varied considerably among the cultivars investigated. Accordingly, different time–temperature regimes were required for their complete in vitro and in situ inactivation. Unexpectedly, thermal inactivation of PPO was disadvantageous regarding pigment and color retention of strawberry purées, which was ascribed to partial regeneration of PPO. Hence, protection of antioxidants, total phenolics and ascorbic acid from oxidative degradation could not be achieved by heating the purées prior to storage.     

A multiscale parallel computing architecture for automated segmentation of the brain connectome

Several groups in neurobiology have embarked into deciphering the brain circuitry using large-scale imaging of a mouse brain and manual tracing of the connections between neurons. Creating a graph of the brain circuitry, also called a connectome, could have a huge impact on the understanding of neurodegenerative diseases such as Alzheimer's disease. Although considerably smaller than a human brain, a mouse brain already exhibits one billion connections and manually tracing the connectome of a mouse brain can only be achieved partially. This paper proposes to scale up the tracing by using automated image segmentation and a parallel computing approach designed for domain experts. We explain the design decisions behind our parallel approach and we present our results for the segmentation of the vasculature and the cell nuclei, which have been obtained without any manual intervention.     

Vacuum-processed polyethylene as a dielectric for low operating voltage organic field effect transistors

We report on the fabrication and performance of vacuum-processed organic field effect transistors utilizing evaporated low-density polyethylene (LD-PE) as a dielectric layer. With C₆₀ as the organic semiconductor, we demonstrate low operating voltage transistors with field effect mobilities in excess of 4 cm²/Vs. Devices with pentacene showed a mobility of 0.16 cm²/Vs. Devices using tyrian Purple as semiconductor show low-voltage ambipolar operation with equal electron and hole mobilities of ～0.3 cm²/Vs. These devices demonstrate low hysteresis and operational stability over at least several months. Grazing-angle infrared spectroscopy of evaporated thin films shows that the structure of the polyethylene is similar to solution-cast films. We report also on the morphological and dielectric properties of these films. Our experiments demonstrate that polyethylene is a stable dielectric supporting both hole and electron channels.     

CARD9 Deficiency Increases Hippocampal Injury Following Acute Neurotropic Picornavirus Infection but Does Not Affect Pathogen Elimination

Neurotropic viruses target the brain and contribute to neurologic diseases. Caspase recruitment domain containing family member 9 (CARD9) controls protective immunity in a variety of infectious disorders. To investigate the effect of CARD9 in neurotropic virus infection, CARD9^−/− and corresponding C57BL/6 wild-type control mice were infected with Theiler’s murine encephalomyelitis virus (TMEV). Brain tissue was analyzed by histology, immunohistochemistry and molecular analyses, and spleens by flow cytometry. To determine the impact of CARD9 deficiency on T cell responses in vitro, antigen presentation assays were utilized. Genetic ablation of CARD9 enhanced early pro-inflammatory cytokine responses and accelerated infiltration of T and B cells in the brain, together with a transient increase in TMEV-infected cells in the hippocampus. CARD9^−/− mice showed an increased loss of neuronal nuclear protein⁺ mature neurons and doublecortin⁺ neuronal precursor cells and an increase in β-amyloid precursor protein⁺ damaged axons in the hippocampus. No effect of CARD9 deficiency was found on the initiation of CD8⁺ T cell responses by flow cytometry and co-culture experiments using virus-exposed dendritic cells or microglia-enriched glial cell mixtures, respectively. The present study indicates that CARD9 is dispensable for the initiation of early antiviral responses and TMEV elimination but may contribute to the modulation of neuroinflammation, thereby reducing hippocampal injury following neurotropic virus infection.     

Determination of hemin-binding characteristics of proteins by a combinatorial peptide library approach

Studies of the binding of heme/hemin to proteins or peptides have recently intensified as it became evident that heme serves not only as a prosthetic group, but also as a regulator and effector molecule interacting with transmembrane and cytoplasmic proteins. The iron‐ion‐containing heme group can associate with these proteins in different ways, with the amino acids Cys, His, and Tyr allowing individual modes of binding. Strong coordinate‐covalent binding, such as in cytochrome c, is known, and reversible attachment is also discussed. Ligands for both types of binding have been reported independently, though sometimes with different affinities for similar sequences. We applied a combinatorial approach using the library (X)₄(C/H/Y)(X)₄ to characterize peptide ligands with considerable hemin binding capacities. Some of the library‐selected peptides were comparable in terms of hemin association independently of whether or not a cysteine residue was present in the sequence. Indeed, a preference for His‐based (≈39 %) and Tyr‐based (≈40 %) sequences over Cys‐based ones (≈21 %) was detected. The binding affinities for the library‐selected peptides, as determined by UV/Vis spectroscopy, were in the nanomolar range. Moreover, selected representatives efficiently competed for hemin binding with the human BK channel hSlo1, which is known to be regulated by heme through binding to its heme‐binding domain.     

Occurrence of ochratoxin A in cocoa by-products and determination of its reduction during chocolate manufacture

This work reports an investigation carried out to assess the natural occurrence of ochratoxin A in 168 samples from different fractions obtained during the technological processing of cocoa (shell, nibs, liquor, butter, cake and cocoa powder) and the reduction of ochratoxin A during chocolate manufacture. Ochratoxin A analyses were performed with immunoaffinity columns and detection by high performance liquid chromatography. Concerning the natural ochratoxin A contamination in cocoa by-products, the highest levels of ochratoxin A were found in the shell, cocoa powder and cocoa cake. The cocoa butter was the least contaminated, showing that ochratoxin A seems to remain in the defatted cocoa solids. Under the technological conditions applied during the manufacture of chocolate in this study and the level of contamination present in the cocoa beans, this experiment demonstrated that 93.6% of ochratoxin A present in the beans was reduced during the chocolate producing.     

Characterization and Technological Properties of Lactic Acid Bacteria in the Production of “Sorghurt,” a Cereal-Based Product

A total of 57 predominant LAB strains isolated from cassava and maize grains fermentation processes for fufu and ogi were identified using phenotypic and genomic fingerprinting methods such as rep-PCR and ARDRA. They were divided into facultatively heterofermentative rods (26.3%), obligately heterofermentative rods (31.6%), and tetrad forming homofermentative cocci (42.1%). Selected strains were further identified by sequencing the 16S rDNA gene. Technological studies such as acidification, hydrogen peroxide production, starch hydrolysis, enzymatic activities, degradation of oligosaccharides, and in vitro adherence properties were carried out. Lactobacillus plantarum strains demonstrated better and rapid acid production capability, followed by the Pediococcus strains, while L. fermentum strains exhibited slower acid production. Hydrogen peroxide production was observed among the LAB groups. The test strains utilized the indigestible sugars raffinose and stachyose. Only L. pentosus demonstrated high amylase activity comparable to that of L. amylovorus DSM 20531. Lactobacillus plantarum and L. fermentum strains showed high β-glucosidase activity. Six strains were selected as starter cultures. The strains were tolerant to acidic pH levels and bile salt. The yoghurt-like “sorghurt” produced using the selected starter cultures had a final pH of less than pH 4.0, and a viable count of less than 5.5 Log₁₀cfu/mL at the end of a 24 h fermentation period. The samples were generally acceptable to the taste panelists. The starter organisms demonstrated varying degree of adherence to HT29 MTX cell line. Therefore, employing functionally defined LAB strains may be one practical approach for incorporating health-promoting features into appropriate food products suitable for targeted population.     

Processing, Physicochemical, Nutritional, and Organoleptical Properties of Dackere, an African Cereal/Tuber Food Semolina

Dackere is a granulated food made from tubers or cereals flours by women in rural areas of Northern Cameroon. The processing of the semolina faces some constraints that affect the quality and hence the potential to improve the incomes of producers. The objectives of this work were to identify and characterize the processing steps involved in the production of dackere and evaluate the physicochemical and hedonic characteristics of this food. Four groups of farmers consisting of organized and specialized women in dackere processing were used for this purpose and then followed up in their production site. The results obtained revealed that dackere was manufactured from either tubers or cereals based on the available food materials: sweet potato, cassava, corn, millet, fonio, and mixture of sweet potato/corn. Generally, the processes involved included hydrating the flour with water, granulating manually, steam cooking, and eventually drying. All these processes were done in a non-replicable manner using traditional equipment. The physicochemical characterization revealed that dackeres were in general rich in starch (60.63 to 94.99 g/100 g) and poor in proteins (0.77 to 4.42 g/100 g). Digestible starch varied from 34.9 g/100 g for corn dackere to 66.6 g/100 g for cassava and sweet potatoes dackeres, and the index of whiteness varied from 58.8 for sweet potatoes dackere to 75.8 for cassava and corn dackeres. Significant variations were observed among producers. Consumers more appreciated the sweet potato/corn dackere mixture which was associated by principal component analysis to high swallowing ability, taste, and adherence in mouth. However, they were irregular in size and brown in color, characteristics negatively correlated to acceptability.     

A Micro-manipulation Technique for the Purification of Diatoms for Isotope and Geochemical Analysis

A method is described for the purification and extraction of diatom samples for isotope and geochemical analysis. The technique involves a micro-manipulator attached to an inverted microscope with a cellular micro-injector system used to remove contaminants or separate assemblages into single-species samples. Whilst time consuming, the advances associated with this technique, eliminating issues related to contamination and the impact of species-dependent fractionation factor/isotopic effect, allows ultra-clean as well as species and/or size specific diatom samples to be analysed in palaeoenvironmental research down to seasonal timescale resolution. By further altering the inner dimensions of the commercially available capillary tubes, (3.5–150  $\upmu $ m) this technique can be extended for use with other microfossils including radiolaria (30  $\upmu $ m to 1 mm), pollen (6–100  $\upmu $ m) and phytolith samples (1–200  $\upmu $ m).     

洗衣剂的发展趋势（英）

新用途和多功能产品使洗衣剂除了清洗衣物外,有了更大作用,分析了液体洗涤剂和粉状洗涤剂的市场,正确评估了片状洗涤剂的市场前景,指出,省时和多功能将是洗衣剂未来发展的趋势。